1. Field of the Invention
The present invention relates to an adsorbent for oral administration comprising a surface-modified spherical activated carbon having a specific pore structure. Further, the present invention relates to an agent for treating or preventing a renal or liver disease, comprising the adsorbent for oral administration as an effective component.
The adsorbent for oral administration, according to the present invention, exhibits a high adsorbability of harmful toxins in a body, and therefore, can adsorb many toxins within a given period of time wherein toxins must be adsorbed, during a retention period from the oral administration to an excretion.
2. Description of the Related Art
In patients suffering a lack of a renal function or a liver function, harmful toxic substances are accumulated or formed in bodies, such as blood, with a progress of a disorder of the organ functions, and thus an encephalopathia occurs, such as a disturbance of consciousness or uremia. Yearly, there is a growing number of such patients, and therefore, the development of an organ-substitute apparatus or medicament having a function to remove toxic substances from bodies, in place of such defective organs, has become a serious problem. A method for removing toxic substances by hemodialysis as an artificial kidney is prevalent. Nevertheless, the hemodialysis-based artificial kidney requires a special apparatus, and thus, a skilled specialist is required from a safe operation standpoint. Further, blood must be taken from a patient's body, and thus, there are disadvantages in that patients must bear high physical, mental and economic burdens. Accordingly, hemodialysis is not satisfactory.
As a means of remedying the above disadvantages, an oral adsorbent which can be orally administered and cure a disorder of renal and liver functions was developed and utilized [Japanese Examined Patent Publication (Kokoku) No. 62-11611]. The adsorbent disclosed in Japanese Examined Patent Publication (Kokoku) No. 62-11611 comprises a porous spherical carbonaceous substance having particular functional groups, that is, a surface-modified spherical activated carbon, having a high safety factor and stable to a body, and having a useful selective adsorbability; that is, an excellent adsorbability of harmful substances in the presence of a bile acid in an intestine, and a low adsorbability of useful substances such as digestive enzymes in the intestine. For these reasons, the oral adsorbent is widely and clinically used for a patient suffering from a disorder of a liver or renal function, as an adsorbent having few side effects such as constipation. The above adsorbent disclosed in Japanese Examined Patent Publication (Kokoku) No. 62-11611 was prepared by forming a spherical activated carbon from a pitch such as a petroleum pitch as a carbon source, and then carrying out an oxidizing treatment and a reducing treatment.
Further, Japanese Patent No. 3522708 [Japanese Unexamined Patent Publication (Kokai) No. 2002-308785] discloses an adsorbent for oral administration providing an improvement in the above useful selective adsorbability; that is, an excellent adsorbability of harmful substances and a low adsorbability of useful substances in the intestine. The adsorbent for oral administration disclosed in Japanese Patent No. 3522708 is based on a finding that the above selective adsorbability is improved within a special scope of a pore volume, that is, when a volume of pores having a pore diameter of 20 to 15000 nm is from not less than 0.04 mL/g to less than 0.10 mL/g. The adsorbent for oral administration is very effective in the treating of wherein diseases that a sufficient adsorption of toxins and a reduced adsorption of useful substances in the intestine are desired.